Process for preparing pale-colored and transparent alkyl glycosides

ABSTRACT

A process for preparing pale-colored and transparent alkyl glycosides by reacting glucose and high fatty alcohol in presence of an acid catalyst is disclosed. The process comprises the steps of admixing, reacting, neutralizing, distilling, diluting and bleaching. In the above process, the reaction step is controlled by a product color and an amount of unreacted glucose, the neutralizing step is controlled by alkali metal oxdie powders having a specific surface area of more than 30 m 2 /g and the product color, the distilling step is controlled an unreacted residual fatty alcohol, and the diluting step is controlled by refined ion water and sealed vessel without oxygen. Further, the process provides a method of recycling collected fatty alcohol without being refined.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a process for preparing alkylglycosides, and more particularly to a process for preparingpale-colored and transparent alkyl glycosides.

(b) Description of the Related Art

Alkyl glycosides are non-ionic surfactants made from natural materials,which provide detergency, foaming, emulsifying, and wetting propertiescomparable to those of other non-ionic surfactants. Alkyl glycosideshave an advantage of reducing water pollution as applied to detergentssince they have a superior biodegradability, and also because of theirhypo-allergenic property they are suitable for decreasing allergicreactions of skin commonly associated with the detergents.

Conventionally, alkyl glycosides are prepared by a method of reactingcarbohydrates with low fatty alcohol such as butyl alcohol in presenceof an acid catalyst such as sulfuric acid or hydrochloric acid, and thenreacting carbohydrates with high fatty alcohol as disclosed in GermanPatent Application No. 3 723 826 A1; German Patent Application No. 3 827534 A1; German Patent Application No. 3 842 541 A1; EPO Publication No.0 306 650 A1; EPO Publication No. 0 306 651 A1 and EPO Publication No. 0306 652 A1. Because the method utilizes two reacting steps having a longreaction time, the process becomes complex. Additionally, there is adrawback in that the high fatty alcohol and low fatty alcohol must bestored separately, further complicating the method.

To solve the above problems, EPO Publication No. 0 387 913 A1 and EPOPublication No. 0 388 857 A1 describe a process of reacting carbohydratesuch as glucose with high fatty alcohol in presence of an acid catalyst.This method has a problem in that removing an excess of unreacted highfatty alcohol cause brown color to develop. In the neutralization step,an alkaline substance is added to remove remaining acids from thereaction, in order to prevent the alkyl glycosides from reversiblydecomposing into glucose and alcohol at a high temperature. However, inthe above neutralization step, an exact neutralization point isdifficult to obtain, and consequently adding an alkaline substance inexcess is not an uncommon problem. An excess of alkaline substance inthe above step cause brown color to develop, also attributed by thepresence of carbohydrates, oxygen, high temperature, alkali, proteins,metal ions, minerals or vitamins.

To solve the above problem, U.S. Pat. No. 4,950,743; EPO Publication No.0 362 671 A1; EPO Publication No. 0 389 753 A1; German PatentApplication No. 3 940 827 A1 and German Patent Application No. 4 019 175A1 describe a method of bleaching alkyl glycosides with peroxide such ashydrogen peroxide or ozone (O₃), and stabilizing with sodium borohydride(NaBH₄). This method has problems in that it provides an unsatisfieddegree of color (closest to transparency), and color reversion may occurduring storage of surfactants.

PCT Publication No. WO 94/02494; PCT Publication No. 94/24139 and PCTPublication No. 95/23169 describe methods utilizing a neutralizing agenthaving a weak alkaline substance such as a mixture of sodium hydroxideand magnesium oxide in order to decrease the color reversion. Again,these methods fall short of solving the above problem of removing browncoloration while obtaining a satisfactory degree of color closest totransparency.

Additionally, in the conventional methods, there is a further drawbackin that the removed fatty alcohol, still having brown coloration, cannotbe utilized again until it is refined in a distillation process and haveits color removed. This additional step complicates and adds cost to themanufacturing process.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a process forpreparing pale-colored and transparent alkyl glycosides.

Another object is to provide a process of collecting excess fattyalcohol without a refining step.

To achieve the above objects the present invention provides a processfor preparing pale-colored and transparent alkyl glycosides by reactinga glucose with a high fatty alcohol in presence of an acid catalyst,comprising the steps of admixing, reacting, neutralizing, distilling,diluting and bleaching. In the above process, the reacting step iscontrolled by a product's color and an amount of unreacted glucose; theneutralizing step is controlled by alkali metal oxide powders and theproduct's color; the distilling step is controlled by an unreacted fattyalcohol; and the diluting step is controlled by refined ion water andsealed vessel without oxygen.

Additional objects, advantages and novel features of the invention willbe set forth in part in the description which follows, and in part willbecome apparent to those skilled in the art upon examination of thefollowing or may be learned by practice of the invention. The object andadvantage of the invention may be realized and attained by means of theinstrumentality and combinations particular pointed out in the appendedclaims.

DETAILED DESCRIPTION OF THE INVENTION

The preferred processes according to the present invention will now bedescribed in detail.

A first preferred process for preparing pale-colored and transparentalkyl glycosides according to the present invention comprises the stepsof:

1) admixing a carbohydrate such as glucose with high fatty alcoholhaving 8 to 22 carbon atoms;

2) reacting the mixture in presence of an acid catalyst such asp-toluene sulfonic acid (p-TSA) at a high temperature under a highvacuum condition until the reaction product's color is between ochre andwormwood and the amount of unreacted glucose is less than 3% of thereactants' weight;

3) neutralizing the reaction product having water content of less than1000 ppm by adding neutralizing agent such as alkali metal oxide powdersthat have a specific surface area of more than 30 m²/g, and stirringuntil the reaction product's color is yellow and the reaction product pHis 7.0˜8.0;

4) distilling the neutralized reaction product to remove the unreactedresidual fatty alcohol at a high temperature under a high vacuumcondition until the amount of the unreacted fatty alcohol is less than2% of the distilled reaction product's weight;

5) diluting the distilled reaction product by adding refined ion waterhaving pH of 2.0˜6.0, in a vessel sealed and charged with nitrogen gas;then

6) bleaching the diluted reaction product with a small amount ofbleaching agent such as hydrogen peroxide.

In the above steps, it is preferable that the amount of fatty alcohol instep 1) is 3˜5 mole per mole of glucose; the amount of acid catalyst instep 2) is 0.002˜0.007 mole per mole of glucose; the reactiontemperature is 110˜125° C.; the reaction pressure is 16˜20 torr; and thereaction time is 80˜200 minutes.

The preferred alkali metal oxide of the neutralizing agent in step 3) ismagnesium oxide, aluminum oxide, calcium oxide, zinc oxide or theirmixture and the amount used is between 0.5 mole and 1.0 mole based onthe acid catalyst used. The stirring temperature is between 85° C. and105° C., and the stirring time is between 20 minutes and 40 minutes.

It is also preferable that the distillation instrument in step 4) is athin film evaporator, and that the color of the diluted reaction productin step 5) is yellow having between 4 and 11 Gardner number.

The preferred vessel in step 5) have an outlet operated automatically bya level sensor or a pressure sensor and the dilute concentration isbetween 40% and 60%. Also a residue of the bleaching agent in step 6)may be decreased from the reaction product by a heat exchanger.

A second preferred process according to the present invention will nowbe described below.

1) reacting glucose and high fatty alcohol of having 8 to 22 carbonatoms, in presence of an acid catalyst until the amount of unreactedglucose in reaction product is less than 3% of the distilled reactantproduct' weight;

2) neutralizing the reaction product by adding magnesium oxide powdershaving a specific surface area of more than 50 m²/g, preferably morethan 80 m²/g, at 85˜105° C. temperature for 20˜40 minutes;

3) distilling the neutralized reaction product until the amount of theunreacted residual fatty alcohol is less than 2% of the reactants'weight;

4) diluting the distilled reaction product; then

5) bleaching the diluted reaction product with hydrogen peroxide.

In the above process, it is preferable that the acid catalyst ispara-toluene sulfonic acid in the reacting step and that the amount ofmagnesium oxide used is between 0.5 mole and 1.0 mole, based on the acidcatalyst used.

A third preferred process according to the present invention will bedescribed below.

1) reacting glucose and high fatty alcohol of having 8 to 22 carbonatoms in presence of an acid catalyst until the amount of unreactedglucose in reaction product is less than 3% of the reactants' weight;

2) neutralizing the reaction product having water content of less than1000 ppm, preferably less than 500 ppm, by adding alkali metal oxidepowders such as magnesium oxide, aluminum oxide, calcium oxide, zincoxide or their mixture having a specific surface area of more than 30m²/g, preferably more than 50 m²/g.

In the above process, it is preferable that the amount of alkali metaloxide used is between 0.5 mole and 1.0 mole, based on the acid catalystused, and that the neutralization is carried out by stirring for 20˜60minutes at 85˜105° C. temperature until the pH of the neutralizedreaction product is between 7.0 and 8.0.

A fourth preferred process according to the present invention will bedescribed below.

1) reacting glucose and high fatty alcohol in presence of an acidcatalyst;

2) neutralizing the reaction product by adding neutralizing agent untilthe reaction product' pH is 7.0˜8.0;

3) distilling the neutralized reaction product; then

4) diluting the distilled reaction product by adding refined ion waterhaving pH 2.0˜6.0, preferably pH of 3.0˜5.0, in a vessel sealed andcharged with nitrogen gas.

In the above process, it is preferable that the vessel has an outletoperated automatically by a level sensor or a pressure sensor.

A fifth preferred process according to the present invention will bedescribed below.

1) admixing a carbohydrate such as glucose with high fatty alcoholhaving 8 to 22 carbon atoms;

2) reacting the mixture in presence of an acid catalyst until thereaction product's color is between ochre and wormwood and the amount ofunreacted glucose is less than 3% of the reactants' weight;

3) neutralizing the reaction product by adding magnesium oxide powders,and stirring until the reaction product's color is yellow;

4) distilling the neutralized reaction product until the amount of theunreacted residual fatty alcohol is less than 2% of the distilledreaction product's weight;

5) diluting the distilled reaction product; then

6) bleaching the diluted reaction product with hydrogen peroxide.

In the above steps, it is preferable that the neutralization is carriedout by stirring for 20˜60 minutes at 85˜105° C.

In accordance with the present invention, factors that affect colorquality and cleaning effect of detergents are described below.

The first factor is a length of carbon chain that a fatty alcoholcontains. Generally, alkyl glycosides made from a fatty alcoholcontaining less than 10 carbon atoms have a superior degree of color,and they are very hydrophilic that they may be soluble in water.However, alkyl glycosides made from a fatty alcohol containing more than12 carbon atoms have an inferior degree of color, and they are veryhydrophobic that they are suitable as emulsifying agent or wettingagent. Accordingly, a mixture of both the high and low number carbonchain fatty alcohol is employed as raw materials for a detergent havinga superior degree of color and a cleaning effect.

The second factor is a mole ratio of fatty alcohol to glucose. Forexample, if the mole ratio of fatty alcohol and glucose (A/G) is over 5,the product may have a good degree of color that may be found at the endpoint of reaction without difficulty. However, the product has aninferior cleaning effect because of it's a low degree ofoligomerization. On the other hand, if the mole ratio is below 2 or 3,the product may have an inferior degree of color. Hence, it ispreferable that the reaction mole ratio of fatty alcohol to glucose isbetween 3 to 5 to obtain alkyl glycosides having a superior degree ofcolor and cleaning effect.

The third factor is an oxygenation of reaction product produced at atemperature above 130° C. while removing excess fatty alcohol. Theoxygenation provides final product having an inferior degree of color.

The fourth factor is a neutralizing condition such as pH. In theneutralizing step it is difficult to control pH with a neutralizingagent. If the neutralization is not sufficient, the reaction may bereversed and alkyl glycosides may decompose to glucose and alcohol, andthe isolated glucose becomes a caramel. If the neutralization isexcessive, the product may become an alkaline substance and browncoloration may develop. Hence, it is preferable that pH is maintained ina range of 7.0 to 8.0. The temperature and the time required in theneutralizing step also influence pH and color quality.

Accordingly, it is preferable that in the admixing step the amount offatty alcohol is 3˜5 mole per mole of glucose; that in the reacting stepthe amount of acid catalyst is 0.002˜0.007 mole per mole of glucose; thereaction temperature is 110˜125° C.; the reaction vacuum pressure is16˜20 torr; the reaction time is 80˜200 minutes; and the amount ofunreacted glucose is below 3% of the reactants' weight.

In the neutralizing step of the present invention, a neutralizing agentemployed is alkali metal oxide powders such as magnesium oxide, aluminumoxide, calcium oxide, zinc oxide in an amount between 0.5 mole and 1.0mole, based on the amount of acid catalyst used, on a molar basis. Thestirring temperature range is from 85° C. to 105° C.; stirring time isbetween 20 minute to 40 minute; neutralizing end point range is from pHof 7.0 to 8.0.

In distilling step of the present invention, the reaction productdistilled by heat should have an unreacted fatty alcohol below 2% of thedistilled reaction product's weight. And it is desirable to cool thedistilled reaction product quickly until the product temperature reachesbelow 130° C. for obtaining a superior degree of color. And thecollection of the distilled excess fatty alcohol can be recycled withoutthe refining step.

In the diluting step of the present invention, the controlled reactionproduct color is yellow having Gardner number range of from 4 to 11.

In the bleaching step of the present invention, after removing theresidue of the bleaching agent by a heat exchanger, the product obtainedis pale and transparent color.

The following examples illustrate the advantages of the presentinvention.

EXAMPLE 1

To a vessel with an over head stirrer and addition funnel, was added amixture of fatty alcohol comprised of 22 parts of C₈, 17 parts of C₁₀,47 parts of C₁₂ and 14 parts of C₁₄ by weight. Stirring was started andglucose was admixed. The amount of admixture was 100 kg and a weightratio of fatty alcohol to glucose was 3.5.

155 grams of p-toluene sulfonic acid catalyst was added under vacuum.

The pressure was reduced to 20 torr and the mixture was heated andreacted at a temperature range of from 116° C. to 120° C. for 100minutes.

To this mixture was then added 22 grams of magnesium oxide powdershaving 100 m²/g of specific surface area and 1% moisture content. Themixture was stirred for 30 minutes at a pot temperature of 95° C.

The neutralized mixture was then distilled under a vacuum pressure ofbelow 0.5 torr at a heat temperature of below 200° C. At this point inthe process, the distilled mixture contained an alcohol residue havingless than 2% of the distilled reaction product's weight.

The distilled mixture was then diluted with 34 kg of refined ion waterequal to the amount of distilled mixture.

The diluted solution was found to have water content of 50%, and aGardner color number of 5.4.

To the diluted mixture was added 0.9 kg of 30% aqueous solution ofsodium hydroxide and was dissolved for 10 minute at a pot temperature of50° C. And then, 1.7 kg of 28% aqueous solution of hydrogen peroxide wasadded and stirred for 2 hours at 85° C.

The bleached solution was found to have pale-colored and transparentalkyl glycosides having water content of 49.6%, transmittance of 95% andAPHA of 30 by an examination with naked eye and instrumental analysisusing a tintometer (Lovibond's PFX 190) and transmittance analyser(Milton Roy's spectronic 20 D). The collected alcohol had APHA of 0.

EXAMPLE 2

Alkyl glycosides was obtained by the process steps of Example 1, except25 grams of magnesium oxide powders having 80 m²/g of specific surfacearea and 1% of moisture content was utilized.

The diluted solution was found to have water content of 50%, and aGardner color number of 6.0.

The bleached solution was found to have pale-colored and transparentalkyl glycosides having water content of 49.5%, transmittance of 93%,and APHA of 48. The collected alcohol had APHA of 10.

Comparative Example A

For comparison purposes, alkyl glycosides was obtained by the processsteps of Example 1, except 35 grams of magnesium oxide powders having 30m²/g of specific surface area and 1% of moisture content was utilized.

The diluted solution was found to have water content of 50%, and aGardner color number of 8.7.

The bleached solution was found to have semi-transparent alkylglycosides having water content of 48.6%, transmittance of 60%, and APHAof 80. The collected alcohol had APHA of 20.

Comparative Example B

Alkyl glycosides was obtained by the process steps of Example 1, except62 grams of magnesium oxide powders having 10 m²/g of specific surfacearea and 1% of moisture content was utilized.

The diluted solution was found to have water content of 50%, and aGardner color number of 9.5.

The bleached solution was found to have semi-transparent alkylglycosides having water content of 49.5%, transmittance of 45%, and APHAof 190. The collected alcohol had APHA of 30.

Comparative Example C

Alkyl glycosides was obtained by the process steps of Example 1, except11 grams of magnesium oxide powders having 65 m²/g of specific surfacearea and 1% of moisture content and 104 g of 30% aqueous solution ofsodium hydroxide were utilized.

The diluted solution was found to have water content of 50%, and aGardner color number of 15.5.

The bleached solution was found to have opaque alkyl glycosides havingwater content of 49.5%, transmittance of 25%, and APHA of 320. Thecollected alcohol had APHA of 80.

EXAMPLE 3

To a vessel with an over head stirrer and addition funnel, was added amixture of fatty alcohol comprised of 22 parts of C₈, 17 parts of C₁₀,47 parts of C₁₂ and 14 parts of C₁₄ by weight. Stirring was started andglucose was admixed. The amount of admixture was 100 kg and a weightratio of fatty alcohol to glucose was 3.5.

155 grams of p-toluene sulfonic acid catalyst was added under vacuum.

The pressure was reduced to 20 torr and the mixture was heated andreacted at a temperature range of from 116° C. to 120° C. for 100minutes.

To this mixture was then added 35 grams of magnesium oxide powdershaving 30 m²/g of specific surface area and 1% of moisture content. Themixture was stirred for 30 minutes at a pot temperature of 95° C.

The neutralized mixture was then distilled under a vacuum pressure ofbelow 0.5 torr at a heat temperature of below 200° C. At this point inthe process, the distilled mixture contained an alcohol residue havingless than 2% of the distilled reaction product's weight.

The distilled mixture was then diluted with 34 kg of refined ion waterof pH 4.5 equal to the amount of distilled mixture. The diluting stepwas carried out in the sealed vessel which have an outlet operatedautomatically by a level sensor or a pressure sensor, and nitrogen gaswas poured into the vessel in the beginning of dilution in order toprevent the mixture from being exposed to oxygen.

The diluted solution was found to have water content of 50%, and aGardner color number of 7.2.

To the diluted mixture was added 0.9 kg of 30% aqueous solution ofsodium hydroxide and was dissolved for 10 minute at a pot temperature ofto about 50° C. And then, 1.7 kg of 28% aqueous solution of hydrogenperoxide was added and stirred for 2 hours at 85° C.

The bleached solution was found to have pale-colored and transparentalkyl glycosides having water content of 49.6%, transmittance of 84%,and APHA of 60 by an examination with naked eye and instrumentalanalysis using a tintometer (Lovibond's PFX 190) and transmittaceanalyser (Milton Roy's spectronic 20 D). The collected alcohol had APHAof 20.

Comparative Example D

For comparison purposes, alkyl glycosides was obtained by the processsteps of Example 1, except 35 grams of magnesium oxide powders having 30m²/g of specific surface area and 1% of moisture content was utilized.And the neutralization was carried out for 90 minutes instead of 30minutes, and the neutralized solution color was becoming light yellow orbright yellow.

The diluted solution was found to have water content of 50%, and aGardner color number of 9.2.

The bleached solution was found to have semi-transparent alkylglycosides having transmittance of 54% and APHA of 100. The collectedalcohol was found to have APHA of 35.

EXAMPLE 4

Alkyl glycosides was obtained by the process steps of Example 1, exceptreaction time proceeded until the reaction solution color was betweenochre and wormwood, and 35 grams of magnesium oxide powders having 30m²/g of specific surface area and 1% of moisture content was utilized.And the neutralization was carried out for 30 minutes, and theneutralized solution color was becoming yellow.

The diluted solution was found to have water content of 50%, and aGardner color number of 7.8.

The bleached solution was found to have transparent alkyl glycosideshaving transmittance of 75% and APHA of 70. The collected alcohol hadAPHA of 16.

Comparative Example E

For comparison purposes, alkyl glycosides was obtained by the processsteps of Example 1, except a reaction product having moisture content of1.25% and 35 grams of magnesium oxide powders having 30 m²/g of specificsurface area and 1% of moisture content were utilized. And theneutralization condition was carried out in atmospheric pressure.

The neutralized reaction product was decomposed to alcohol and glucose,and became a caramel owing to oligomerization of glucose in the step ofdistillation.

EXAMPLE 5

Alkyl glycosides was obtained by the process steps of ComparativeExample E, but a vacuum of 150 torr was used in the neutralizing step.

The neutralized reaction product was not found to be a caramel.

The diluted solution was found to have water content of 50%, Gardnercolor number of 8.2.

The bleached solution was found to have transparent alkyl glycosideshaving transmittance of 70%, and APHA of 74. The collected alcohol hadAPHA of 18.

EXAMPLE 6

To a vessel with an over head stirrer and addition funnel, was added amixture of fatty alcohol comprised of 22 parts of C₈, 17 parts of C₁₀,47 is parts of C₁₂ and 14 parts of C₁₄ by weight. Stirring was startedand glucose was admixed. The amount of admixture was 100 kg and a weightratio of fatty alcohol to glucose was 3.5.

155 grams of p-toluene sulfonic acid catalyst was added under vacuum.

The pressure was reduced to 20 torr and the mixture was heated andreacted at a temperature of from 116° C. to 120° C. for 100 minutesuntil the reaction product's color reached between ochre and wormwood.

To this mixture having water content of less than 1000 ppm was thenadded 22 grams of magnesium oxide powders having 100 m²/g of specificsurface area and 1% of moisture content. The mixture was stirred for 30minutes at a pot temperature of 95° C., until the color of neutralizedreaction product became yellow.

The neutralized reaction product was then distilled under a vacuum ofbelow 0.5 torr at a heat temperature of below 200° C. At this point inthe process, the distilled mixture contained an alcohol residue havingless than 2% of the distilled reaction product's weight.

The distilled reaction product was then diluted with 34 kg of refinedion water having 4.5˜5.0 pH. The diluting step was carried out in thesealed vessel which have an outlet operated automatically by a levelsensor or a pressure sensor, and nitrogen gas was poured into the vesselin the beginning of dilution in order to prevent the mixture from beingexposed to oxygen.

This diluted solution was found to have water content of 50%, and aGardner color number of 4.8.

To the diluted mixture was added 0.9 kg of 30% aqueous solution ofsodium hydroxide and was dissolved for 10 minute at a pot temperature of50° C. And then, 1.7 kg of 28% aqueous solution of hydrogen peroxide wasadded and stirred for 2 hours at 85° C.

The bleached solution was found to have pale-colored and transparentalkyl glycosides having water content of 50%, transmittance of 97%, andAPHA (degree of color) of 25 by an examination with naked eye andinstrumental analysis using a tintometer (Lovibond's PFX 190) andtransmittace analyser (Milton Roy's spectronic 20 D). The collectedalcohol had APHA of 0.

In this disclosure, there is shown and described only the preferredprocesses of the invention. But, as aforementioned, it is to beunderstood that the invention is capable of use in various othercombinations and environments and is capable of changes or modificationwithin the scope of the inventive concepts as expressed herein.

What is claimed is:
 1. A process of preparing pale-colored andtransparent alkyl glycosides comprising the steps of: 1) admixingglucose with a high fatty alcohol having 8 to 22 carbon atoms; 2)reacting the mixture in the presence of an acid catalyst at a hightemperature and a high vacuum condition until a reaction product's coloris between ochre and wormwood and an amount of an unreacted glucosereaches below 3% of a reactants' weight; 3) neutralizing the reactionproduct having water content of less than 1000 ppm by means of addingalkali metal oxide powder having a specific surface area of greater than30 m²/g as a neutralizing agent and stirring until the reactionproduct's color is yellow and the reaction product pH is between7.0-8.0; 4) distilling the neutralized reaction product to removeunreacted residual fatty alcohol at a high temperature and a high vacuumcondition until an amount of an unreacted fatty alcohol reaches below 2%of the distilled reaction product's weight; 5) diluting the distilledreaction product by means of adding refined ion water having pH between2.0 and 6.0, in a vessel sealed and charged with nitrogen gas; 6)bleaching the diluted reaction product with a small amount of ableaching agent.
 2. The process according to claim 1, wherein the highfatty alcohol in step 1) is in an amount of 3˜5 mole per mole ofglucose.
 3. The process according to claim 1, wherein the acid catalystin step 2) is in an amount of 0.002˜0.007 mole per mole of glucose. 4.The process according to claim 1, wherein the reaction in step 2) isconducted at a temperature range of 110˜125° C.
 5. The process accordingto claim 1, wherein the reaction in step 2) is conducted under a vacuumpressure of 16˜20 torr.
 6. The process according to claim 1, wherein thereaction in step 2) is conducted for 80˜200 minutes.
 7. The processaccording to claim 1, wherein the alkali metal oxide powder of theneutralizing agent in step 3) is magnesium oxide, aluminum oxide,calcium oxide, zinc oxide or their mixture.
 8. The process according toclaim 1, wherein the neutralizing agent in step 3) is in an amount offrom 0.5 mole to 1.0 mole, based on the acid catalyst used, on a molarbasis.
 9. The process according to claim 1, wherein the stirring processin step 3) is conducted at 85˜105° C.
 10. The process according to claim1, wherein the stirring process in step 3) is conducted for 20 minutesto 40 minutes.
 11. The process according to claim 1, wherein thedistillation process in step 4) is carried out by a thin filmevaporator.
 12. The process according to claim 1, wherein the dilutedreaction product in step 5) is of yellow color having a Gardner numberranging from 4 to
 11. 13. The process according to claim 1, wherein thedilution in step 5) is conducted in a concentration of 40˜60%.
 14. Theprocess according to claim 1, wherein a residue of the bleaching agentin step 6) is decreased from the reaction product by a heat exchanger.15. The process according to claim 1, wherein the removed residual fattyalcohols are collected and recycled without being refined.
 16. A processof preparing pale-colored and transparent alkyl glycosides comprisingthe steps of: 1) reacting glucose and a high fatty alcohol of having 8to 22 carbon atoms in the presence of an acid catalyst until an amountof an unreacted glucose in reaction product reaches less than 3% of areactants weight; 2) neutralizing the reaction product by means ofadding magnesium oxide powders having a specific surface area of greaterthan 50 m²/g at a temperature of 85-105° C. for 20-40 minutes until pHof the reaction product is between 7.0-8.0; 3) distilling theneutralized reaction product until an amount of an unreacted residualfatty alcohol reaches less than 2% of a distilled reaction productsweight; 4) diluting the distilled reaction product; and 5) bleaching thediluted reaction product with hydrogen peroxide.
 17. The processaccording to claim 16, wherein the acid catalyst in step 1) ispara-toluene sulfonic acid (p-TSA).
 18. The process according to claim16, wherein the magnesium oxide in step 2) is in an amount of from 0.5mole to 1.0 mole, based on the acid catalyst used, on a molar basis. 19.The process according to claim 16, wherein the magnesium oxide in step2) has a specific surface area of greater than 80 m²/g.
 20. The processaccording to claim 16, wherein the distillation process in step 3) iscarried out by a thin film evaporator.
 21. The process according toclaim 16, wherein the removed residual fatty alcohols are collected andrecycled without being refined.
 22. A process of preparing pale-coloredand transparent alkyl glycosides comprising the steps of: 1) reactingglucose and a high fatty alcohol of having 8 to 22 carbon atoms inpresence of an acid catalyst until an amount of an unreacted glucose inreaction product reaches less than 3% of a reactants weight; 2)neutralizing the reaction product having water content of less than 1000ppm by means of adding alkali metal oxide powders selected from thegroup consisting of magnesium oxide, aluminum oxide, calcium oxide, zincoxide, and their mixture, having a specific surface area of more than 30m²/g, until pH of the reaction product is between 7.0-8.0.
 23. Theprocess according to claim 22, wherein the alkali metal oxide in step 2)is in an amount of from 0.5 mole to 1.0 mole, based on the acid catalystused, on a molar basis.
 24. The process according to claim 22, whereinthe alkali metal oxide in step 2) has a specific surface area of greaterthan 50 m²/g.
 25. The process according to claim 22, wherein theneutralization in step 2) is carried out by stirring for 20-60 minutesat a temperature of 85-105° C.
 26. The process according to claim 22,wherein the reaction product in step 2) has water content of less than500 ppm.
 27. The process according to claim 22, wherein the removedresidual fatty alcohols are collected and recycled without beingrefined.
 28. A process of preparing pale-colored and transparent alkylglycosides comprising the steps of: 1) reacting a glucose and a highfatty alcohol in presence of an acid catalyst; 2) neutralizing thereaction product by means of adding neutralization agent until thereaction product pH reaches 7.0˜8.0; 3) distilling the neutralizedreaction product; then 4) diluting the distilled reaction product bymeans of adding refined ion water having pH range of 2.0˜6.0, in avessel sealed and charged with nitrogen gas.
 29. The process accordingto claim 28, wherein the refined ion water has pH range of 3.0˜5.0. 30.The process according to claim 28, wherein the vessel in step 4) has anoutlet operated automatically by a level sensor or a pressure sensor.31. The process according to claim 28, wherein the removed residualfatty alcohols are collected and recycled without being refined.
 32. Aprocess of preparing pale-colored and transparent alkyl glycosidescomprising the steps of: 1) admixing glucose and a high fatty alcoholhaving 8 to 22 carbon atoms; 2) reacting the mixture in presence of anacid catalyst until a reaction product's color is between ochre andwormwood and an amount of an unreacted glucose reaches less than 3% ofreactants' weight; 3) neutralizing the reaction product by means ofadding magnesium oxide powders and stirring until the reaction product'scolor is yellow and the reaction product pH is between 7.0-8.0; 4)distilling the neutralized reaction product until an amount of anunreacted residual fatty alcohol reaches less than 2% of the distilledreaction product's weight; 5) diluting the distilled reaction product;then 6) bleaching the diluted reaction product with hydrogen peroxide.33. The process according to claim 32, wherein the neutralizing processis carried out by stirring for 20˜60 minutes at 85-105° C.
 34. Theprocess according to claim 32, wherein the removed residual fattyalcohols are collected and recycled without being refined.